Google (Symbol: GOOG) missed earnings expectations yesterday and that gave shareowners a moment of pause. In after-hours trading on Thursday, Google began declining.

Today (Friday) was actually a great day to get into Google or acquire more shares. In intraday trading, Google fell to $509.50, which was almost 8% lower than Thursday’s close of $548.51.

The last time Google saw $509 was a month ago when it closed at $509.97 on June 20, 2007.

Smart investors should have seen this dip coming. There’s a lot of stress built into Google’s stock and even the slightest whisper of the unexpected will send it lower.

Google reported $3.56 per share on $2.72 billion net revenue, which was slightly off from Wall Street’s expectation of $3.59 per share from $2.68 billion net revenue.

Missing expectations in January 2006, shares were sent lower immediately, but they eventually recovered and moved higher in the coming days, weeks and months.